I'm making a Mandelbrot set viewer in JavaFX. It takes a while, like maybe 5 seconds to finish. Here's my code:

package sample;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class Main extends Application {
    private static int MAX_ITER = 80;
    private static double w = 10*100;
    private static double h = 2*Math.PI*100;

    static double RE_START = -2;
    static double RE_END = 1;
    static double IM_START = -1;
    static double IM_END = 1;

    public static int mandelbrot(Complex c) {
        Complex z = new Complex(0,0);
        int n = 0;
        while (Complex.abs(z).isLessThanOrEqual(2) && n < MAX_ITER) {
            z = Complex.add(Complex.multiply(z,z),c);
        return n;

    public void start(Stage primaryStage) {
        Group root = new Group();
        primaryStage.setTitle("Mandelbrot Viewer");
        primaryStage.setScene(new Scene(root, w, h));

        Canvas canvas = new Canvas();
        GraphicsContext gc = canvas.getGraphicsContext2D();
        canvas.relocate(0, 0);

    private static void update(GraphicsContext gc) {
        for (int x = 0; x < w; x++) {
            for (int y = 0; y < h; y++) {
                Complex c = new Complex(RE_START + (x / w) * (RE_END - RE_START),
                        IM_START + (y / h) * (IM_END - IM_START));
                int m = mandelbrot(c);
                int hue = 360 * m / MAX_ITER;
                int saturation = 255;
                int value = 0;
                if (m < MAX_ITER) {
                    value = 255;
                gc.setFill(Color.hsb(hue, saturation/255d, value/255d));
                gc.fillRect(x, y, 1, 1);

    public static void main(String[] args) {

    static class Complex {
        double r;
        double i;

        Complex(double r, double i) {
            this.r = r;
            this.i = i;

        static public Complex abs(Complex c) {
            return new Complex(Math.abs(c.r), Math.abs(c.i));

        public boolean isLessThanOrEqual(double n) {
            if (r <= n || i <= n) {
                return true;

            return false;

        static public Complex add(Complex c1, Complex c2) {
            return new Complex(c1.r + c2.r, c1.i + c2.i);

        static public Complex multiply(Complex c1, Complex c2) {
            return new Complex((c1.r*c2.r)-(c1.i*c2.i), (c1.r*c2.i)+(c1.i*c2.r));

        public String toString() {
            return (r + ", " + i);

I eventually want it so that I can move around and zoom into the mandelbrot set with at least 10 fps. How might I be able to make it faster? Should I try switching from JavaFX to AWT or something? Should I try using the GPU? if so, what would be the most simple way to do so? (because I don't really want to spend too much time on this project)

  • 1
    \$\begingroup\$ How many instances of Complex class do you create per frame? \$\endgroup\$ – TorbenPutkonen Nov 17 at 14:43
  • 2
    \$\begingroup\$ From a frustrated benchmark (can't seem to get an execution profile), almost no time is consumed by mandelbrot(). (I doubt that the instantiation rate of small instances forgotten before the next is instantiated currently impacts time (for the record, Colors get instantiated frequently (less of a problem) and set for gc (more of one)).) \$\endgroup\$ – greybeard Nov 17 at 14:52
  • 1
    \$\begingroup\$ Thanks. Looking more closely the problem is writing single pixels using the fillRect function. Instead of operating on GraphicsContext create an array of integers to represent the image. There's a lot of info in StackOverflow about how to do that. \$\endgroup\$ – TorbenPutkonen Nov 17 at 15:44
  • \$\begingroup\$ Should I try using BufferedImages and draw them on the canvas instead? would that help? @greybeard \$\endgroup\$ – Samuel Shifrin Nov 17 at 21:37
  • \$\begingroup\$ That seems to be what SuperFractalThing uses - I have never been up to speed with Java performance graphics. \$\endgroup\$ – greybeard Nov 17 at 23:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.